Controversial 'code red' drill concludes at Cary-Grove High School

But she also recommended that those involved sit down afterward and talk about what happened and the feelings the drill evoked.

One Texas school district has increased the realism in its crisis drills, which also serve as training opportunities for police.

At Creekview High School in Carrollton, a designated group of participants recently mimicked a hostage situation in which a student wielded a blue plastic gun before police were called to the scene. Student "victims" wearing signs reading "I've been shot" dropped to the floor, said Angela Shelley, spokeswoman for Carrollton-Farmers Branch Independent School District, just north of Dallas.

While parents, students and teachers knew in advance that some type of drill would take place over the course of a few weeks, few knew exactly when or how it would unfold, Shelley said. Even police who responded to a 911 call did not know they were participating in a drill until they arrived at the campus.

There, police officers informed of the drill set up a blockade to stop the first responders.

"They frisk them, and give them fake guns," said Shelley, who said the officers then proceed into the building to complete the training exercise. "They take every weapon off their body. Then they tag them with a blue tag, so they know they are clear."

One day after Creekview's hostage-taking drill, Adam Lanza shot 20 students and six educators before taking his own life at Sandy Hook.

"The kids take this seriously," Shelley said of the drills. "We do this pretty regularly. They know what to do."

Lisa Black is a staff reporter; Amanda Marrazzo is a freelance reporter.